Channel change response time, also known as channel zapping response time, is the time that is required for a user terminal to switch from one television channel to another television channel in response to a channel change request initiated by a user. In existing digital television systems, such as Internet Protocol Television (IPTV) systems, the channel zapping response time is often quite large (possibly even on the order of seconds). Disadvantageously, such large channel zapping response times significantly reduce the quality of experience (QoE) of users of digital television systems, who have often become accustomed to smaller channel zapping response times of traditional television systems.
While some mechanisms to improve zap response time have been proposed, these mechanisms fall short in one or more of the following dimensions: (1) the amount of additional bandwidth requirements imposed on the network, (2) the ability to efficiently dimension the network to handle worst case load, (3) the degree to which zap response time is lowered in the best, average, and worst case scenarios, (4) introduction of user-perceivable picture distortions resulting from the zap process, and (5) applicability of the mechanism to all types of access systems (e.g., cable television systems, digital subscriber line systems, and FTTx).